The background is good. Nice and consistent (apart from a few breaks in lines here and there) and cartoony.
The rabbits need work. Both of them are awkward in pose and overall anatomy. I’d suggest using some kind of a reference next time (be it a person, rabbit, or hell – a dog standing on it’s hind legs, just something real) to make their stances more believable. Coloring was done well.

Edit: Just saw your last post… Y’know, that’s not a great way to get feedback.

The colours could do with more tones, as they’re kinda flat at the moment. Some shadows and highlights on the greens and browns would look good.

Really, there’s nothing spectacular about the piece, and it overall just feels empty, despite having so much going on. Maybe that’s due to the lack of a clear focal point? Really define where the focal is more. In this instance, you could add more detail to the rabbits, or position them on the rule of thirds, for example.

It’s probably a mockup since it takes me a hour to make a single sprite/tile.

But hey, the real mockup is what the Epic Games did with the game.

They started Jazz Jackrabbit 2 and sold it without even ultimating it. (missing background layers, unused sprites, unfitting music for the Inferno Night level, no difference between difficulties) Then they made a Jazz Jackrabbit 3 demo, but never made the complete game. And a short time ago, they have admitted that they would never ever make a new Jazz Jackrabbit game, and what’s most, they keep the copyrights for it, so nobody in the world may make a commercial Jazz Jackrabbit game. (don’t know if it counts for flash games)

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